1. Field of the Invention
This invention relates to gypsum board and is particularly directed to the production of gypsum board of variable yet predictable density by a continuous process in which fibrous stucco is incorporated in the board.
2. Description of the Prior Art
In the production of gypsum board products, gypsum stucco, which is also referred to as calcined gypsum and which is calcium sulfate hemihydrate (CaSO.sub.4 .multidot.1/2H.sub.2 O), and other additives are admixed with water to make a slurry which is then formed into the desired shape, allowed to set and dried. The standard calcined gypsum or gypsum stucco conventionally used in producing gypsum boards is prepared according to the standard prior art process in a kettle, flash or rotary calciner at normal atmospheric pressures. The setting is a hydration reaction converting the stucco to set gypsum which is calcium sulfate dihydrate (CaSO.sub.4 .multidot.2H.sub.2 O). In conventional manufacturing, the boards produced have densities within a fairly narrow range of from about 1650 lb/MSF to 1900 lb/MSF. It would be highly desirable if a way could be found to produce an acceptable board product having a variable yet predictable density. A lightweight yet strong board would be especially useful.